Why do teenage girls have baby fevers?

I'm so confused about these kind of posts, I see them almost everyday. "I'm 14 and I want a baby", I'm all like "huh?!" 
I don't know if there are any reasons behind wanting a baby when you're a teenager because I really can't see why someone would want a baby at such a young age. I'll turn 18 in a month and everytime I see a baby I'm all like "okay that's not cute.." Maybe I can't see the point because I literally hate babies and I'm thinking about getting my tubes tied or even sterilisation in a few years when I will have a relationship. 
But can someone explain to me all this bebu fever thing? If there is actually an explanation of all of this